1. Field of the Invention
The present invention relates to slurry for CMP (Chemical Mechanical Polishing) and a method of manufacturing a semiconductor device. More specifically, the invention relates to CMP slurry capable of reducing scratches on a region to be polished during the CMP process and a method of manufacturing a semiconductor device.
2. Description of the Related Art
Various microfabrication technologies have recently been developed in accordance with high packing density of semiconductor devices and miniaturization of semiconductor elements. Of the microfabrication technologies, a CMP technology is indispensable to formation of damascene interconnection.
The current metal damascene interconnection process requires CMP whose polishing speed is high and which causes few erosions (hollows made by polishing) and scratches (flaws and cracks). The reason is as follows. The polishing speed should be increased to enhance throughput and the erosions and scratches of interconnections and interlayer insulators should be reduced to form a high-performance interconnection.
The characteristics of CMP depend chiefly upon slurry and a polishing pad. The polishing pad needs to be hardened to a certain degree in order to reduce erosions. With a polishing pad that is softer than a hard pad (IC1000-Pad) that is currently on the market by Rodel, the reduction in erosions is considered to be difficult using whatever slurry.
Though the hard pad can reduce erosions, a number of scratches are caused on a metal interconnection and an insulation film in which the metal interconnection is filled, due to coarse particles such as abrasives contained in slurry and an aggregation of residues caused by polishing. The scratches cause a film to peel off.
Under present circumstances, there is a tradeoff relationship between a reduction in erosions and a reduction in scratches. Most of scratches on an insulation film are made by abrasives, while most of scratches on a metal interconnection are made by an aggregation caused by a deteriorated layer or a protection film (e.g., a metal oxide or complex compound) that is formed on the surface of the interconnection during polishing. The deteriorate layer comes off the outer edge of the substrate.
In the prior art CMP described above, the hard pad can reduce the erosions but the scratches are difficult to reduce at the same. It has been therefore desired that CMP slurry capable of virtually reducing scratches is accomplished and so is a method of manufacturing a semiconductor device using the CMP slurry.